Aopen AP5V FAQ
Appendix B
BIOS revision
(AP53-3)
Frequently Asked Question
Note: FAQ may be updated without notice. If
you cannot find the information that you need in
this appendix, visit our WWW home page,
(address: http://www.aopen.com.tw) and check
the FAQ area and other new information.
Q: How can I identify the mainboard BIOS version?
A: The AOpen mainboard BIOS version appears on the upper-left corner of the
POST (Power-On Self Test) screen. Normally, it starts with R and is found in
between the model name and the date. For example:
AP53/AX53 R3.80 Oct.22.1996
Q: How can I identify version of the mainboard?
A: The AOpen mainboard version appears as ppppp-x on the PCB, near the PCI
slot and is enclosed in a white bordered box. The ppppp is the project code
used by AOpen internally and -x is the version code. For example, for AP53
with 95140 project code and -3 version code, the mainboard version appears
on the PCB as follows:
AP53 95140-3 MADE IN TAIWAN
MB verison -3
B-1
Frequently Asked Questions
Q: Why the AOpen mainboards (MB) do not have cache module expansion
slot?
A: Faster CPU speed requires more difficult and complex MB timing design.
Every trace and components delay must be taken into consideration. The
expansion cache slot design will cause 2 or 3ns delay in PBSRAM timing, and
the extended trace length to the cache module through the golden finger will
further delay the timing by 1 or 2ns. This may result in unreliable system
once the cache module and slot becomes worn. All AOpen MBs support
512KB PBSRAM onboard. For better performance (around 3% higher than
256KB), we strongly recommend you to use 512KB onboard. Otherwise,
reliable 256KB is better than unreliable 512KB with cache module. AOpen is
the first company to promote this concept since the fourth quarter of 1995.
Q: Why do AOpen MBs have two regulators onboard?
A: Heat dissipation becomes a big problem when CPU speed increases. New
generation CPUs use lower voltage or split power plane to reduce power
dissipation. If you use dual-power PP/MT (P55C) CPU, then you need
separate requlators for 3.3V CPU io voltage and 2.8V CPU core voltage.
Refer to section 2.2 "Jumper Settings" for voltage of current CPUs available
on the market. Theoretically, the more regulators, the more reliable power
becomes. For VX chipset MB (AP5V), we even incorporated a third requlator
to support SDRAM. AOpen fully supports PP/MT and SDRAM in its product
line and this puts them ahead among other companies. There is one
exception, ATX MB may use 3.3V power from ATX power supply, it is
possible to reduce one regulator.
Q: What is the difference of Linear Regulator and Switching Regulator?
A: Switching regulator turns on/off Power FET with very high frequency and uses
L/C charge and discharge circuit to do voltage drop. The efficient is better but
voltage ripple and EMI noise is higher. The reason for mainboard designer to
consider switching regulator, is simply because they are worry about linear
regulator can not fully support the coming new CPU. Actually, this depends
on the design and layout quality of mainboard manufacturer. According to
AOpen RD's testing, Intel PP/MT-233, AMD K6-166/200/233 are all fine on
AP5T to run winstone97. (The CPU is at 53 degree C, heatsink is at 60
degree C and regulator IC is at 79 degree C). But for future CPU (perhaps
CPU of 1998), AOpen will still consider to phase-in switching regulator on
new version mainboard.
B-2
Frequently Asked Questions
Q: What is MMX?
A: MMX is the new single-line multiple-instruction technology of the new Intel
Pentium PP/MT (P55C) and Pentium II (Klamath) CPU. The AMD K6 and
Cyrix M2 will support MMX too. The MMX instructions are specifically useful
for multimedia applications (such as 3D video, 3D sound, video conference).
The performance can be improved if applications use these instructions. All
AOpen MBs have at least dual power onboard to support MMX. It is not
necessary to have special chipset for MMX CPU.
Q: What is USB (Universal Serial Bus)?
A: USB is a new 4-pin serial peripheral bus that is capable of cascading
low/medium speed peripherals (less than 10Mbit/s) such as keyboard,
mouse, joystick, scanner, printer and modem/ISDN. With USB, the traditional
complex cables from back panel of your PC can be eliminated.
You need the USB driver to support USB device(s). AOpen MBs are all USB
ready, you may get latest BIOS from AOpen web site
(http://www.aopen.com.tw). Our latest BIOS includes the keyboard driver
(called Legacy mode), that simulates USB keyboard to act as AT or PS/2
keyboard and makes it possible to use USB keyboard if you don't have driver
in your OS. For other USB devices, you may get the drivers from your
device vendor or from OS (such as Win95). Be sure to turn off "USB Legacy
Support" in BIOS "Chipset Setup" if you have another driver in your OS.
Q: What is P1394?
A: P1394 (IEEE 1394) is another standard of high-speed serial peripheral bus.
Unlike low or medium speed USB, P1394 supports 50 to 1000Mbit/s and can
be used for video camera, disk and LAN. Since P1394 is still under
development, , there is no P1394 device currently available in the PC market.
Also, there is no chipset that can support P1394. Probably in the near future,
a card will be developed to support P1394 device.
Q: What is SMBus (System Management Bus, also called I2C bus)?
A: SMBus is a two-wire bus developed for component communication
(especially for semiconductor IC). It is most useful for notebook to detect
component status and replace hardware configuration pin (pull-high or pullÂlow). For example, disabling clock of DIMM that does not exist, or detecting
battery low condition. The data transfer rate of SMBus is only 100Kbit/s, it
allows one host to communicate with CPU and many masters and slaves to
send/receive message. The SMBus may be used for jumpless mainboard, the
components which support SMbus are not ready yet, we will keep eyes on it.
Q: When can we have real jumperless mainboard?
A: PnP had achieved the goal of jumperless add-on card, but true jumperless
mainboard still has some technical concerns. For example, CPU clock and
B-3
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